The present invention relates to touch switch devices and in particular to multiple stacked touch switches which may be simultaneously closed by the application of a single transverse touching force.
Switching devices which are operable in response to application of a transverse touching force are well known. Frequently, however, it is desirable to perform several independent switching functions simultaneously upon the application of a single transverse touch force. For example, battery-powered musical instruments have recently been developed wherein keyboards consist of touch-sensitive switches interconnected in resistive networks to thereby replace strings or keys utilized on conventional instruments. In such instruments it is frequently desirable to use metal oxide semiconductor technology (MOS). However, as is well known, MOS circuitry requires substantial amounts of power even if an input signal has been entirely disconnected by the opening of a switch. Hence, batteries are quickly drained of power and require frequent replacement even when the instrument has not been played but is on.
It is therefore desirable to provide a dual or multifunction switch which will perform the function of both connecting power to the circuitry and connecting or applying the input signal to the circuitry only when the touch-sensitive switch is depressed by a transverse touching force.
In another embodiment of the invention a semiconductor composition layer can be disposed on one or more of the contact surfaces of one or more of the stacked switches to thereby interpose a resistance in series with the switch. The resistance in a preferred embodiment will be variable in response to variations in the transverse touching force.